Scott Alexander on donating one of his kidneys to a stranger

Scott Alexander in Astral Codex Ten:

In polls, 25 – 50% of Americans say they would donate a kidney to a stranger in need.

This sentence fascinates me because of the hanging “would”. Would, if what? A natural reading is “would if someone needs it”. But there are 100,000 strangers on the waiting list for kidney transplants. Between 5,000 and 40,000 people die each year for lack of sufficient kidneys to transplant. Someone definitely needs it. Yet only about 200 people (0.0001%) donate kidneys to strangers per year. Why the gap between 25-50% and 0.0001%?

Some of you will suspect respondents are lying to look good. But these are anonymous surveys. Lying to themselves to feel good, then? Maybe. But I think about myself at age 20, a young philosophy major studying utilitarianism. If someone had asked me a hypothetical about whether I would donate a kidney to a stranger in need, I probably would have said yes. Then I would have continued going about my business, never thinking of it as a thing real-life people could do.

More here.